1. Field of the Invention
This invention relates generally to methods of scrolling on a touchpad. Specifically, the invention relates to a method of activating a scrolling function by performing touchdown in a pre-defined location, and then controlling various scrolling functions by using gestures to control the direction of scrolling.
2. Description of Related Art
As portable electronic appliances become more ubiquitous, the need to efficiently control them is becoming increasingly important. The wide array of electronic devices that can benefit from a means of controlling scrolling include, but should not be considered limited to, MP3 players, portable video players, digital cameras and camcorders, mobile telephones, and other portable devices. However, even desktop devices such as desktop computers can take advantage of a method of scrolling that is quick and efficient.
One of the main problems that many portable electronic appliances have is that their very size limits the number of ways in which communicating with the appliances is possible. There is typically a very limited amount of space that is available for an interface when portability is so important. For example, mobile telephones that require a telephone number keypad are now replacing many personal digital assistants (PDAs). Typically, PDAs require a keyboard for data entry. The inventors of the present invention were involved in the discovery and development of a touchpad that is disposed underneath a telephone keypad. Hiding the keypad under the telephone keymat made the best possible use of the limited space available for data entry.
Other developers and users of portable electronic appliances have seen the benefits that come from using a circular touchpad. The very nature of a circular touchpad enables continuous circular motion in a same direction. However, a circular touchpad typically provides less functionality for other touchpad functions, such as cursor manipulation. Thus, it would be an advantage to provide improved scrolling functions on a typical rectangular or even a square touchpad shape.
Consider a personal digital assistant (PDA). A PDA often has to provide a full keyboard in order to enter characters from an alphabet. Even more difficult is the problem of having to deal with graphical interfaces. PDAs and even mobile telephones are becoming small but portable computers with all of the information that might be carried in a larger computing device. Furthermore, graphical interfaces present some unique challenges when providing a user interface.
The difficulties described are not unique to PDAs and mobile telephones. Even less complex devices are being pressed to provide more and more functionality. Consider an MP3 audio player that enables a user to list items such as songs, and then move through that list in order to select a song to play, or to move to a playlist.
One feature of these portable electronic appliances that is common to all of those listed above and other appliances not mentioned or which are under development, is the need to quickly and easily move or scroll through lists and make selections. It should be noted that all of the portable electronic appliances listed above have or will soon have touchpads disposed somewhere on or within the appliances. This evolution is only natural considering the complex functions and graphical interfaces that they use. However, these portable electronic appliances presently lack a means for providing better control when scrolling through lists.
Thus, it would be an improvement over the prior art to provide a system and method for providing rapid access to scrolling through a list.
When considering how to provide a scrolling feature, it should be realized that an important issue to consider is the size or range of the list that will be used. For example, it may be desirable to control a portable electronic appliance where the lists are very large, and it may be advantageous to move fast and slow while using the same device. For example, the number of songs that can be stored on many MP3 players is now into the thousands. Being able to rapidly move to a song location may require a lot of time, depending upon the interface that is provided for scrolling.
A good analogy to this situation is tuning a radio that has a wide dynamic range. A radio typically has a simple hand-operated control. Tuning a radio to frequency 95.1 MHz over an entire range of 85-105 MHz is to control 1 part in 200. Using a single-turn “knob” or potentiometer, a single turn or revolution of the knob changes the frequency setting from a minimum of 85 MHz to maximum of 105 MHz. Thus, it becomes obvious why it is very hard to get the “fine” control that is necessary to dial into 0.1 MHz resolution. Fine and coarse control can also be thought of as slow and fast incrementing or decreasing of values.
Prior art solutions for this problem have included a multi-turn potentiometer or knob. In this scenario, the knob can be turned multiple revolutions where one revolution might be equal to 2 MHz. In this way, it becomes much easier to dial in 0.1 MHz resolution (i.e., 0.1/2.0=> 1/20th revolution). But now a new problem has arisen. In order to move over the entire frequency range of 20 MHz will now require ten complete turns of the knob, which now becomes an annoyingly slow procedure. Interestingly, most radios and many industrial controls rely on this “many-turns-of-the-knob” solution.
Another prior art solution is to provide two knobs. One knob is for coarse control, and the other knob is for fine control. This solution is apparently common for industrial or laboratory equipment, but it is rare for consumer devices. This disparity is a good example of the fact that it is not user friendly or impossible because of space constraints to provide more controls.
Thus, the problem becomes one of being able to provide the ability to move quickly over the entire dynamic range in a single turn, while at the same time being able to easily change an operating mode from a coarse tuning mode to a fine tuning mode and thus dial-in quickly to a fine resolution.
Accordingly, what is needed is a system and method for providing user input using a touchpad where the manner in which a pointing object touches the touchpad enables fine or coarse input, without having to resort to other mechanisms for changing the resolution of input.
The present invention solves more than just the problem of scrolling through lists. The present invention can be applied to controls that are used in any type of system that can receive input from an electronic or mechanical knob. If a system can be coupled to a touchpad, the touchpad can provide coarse or fine input that is presently provided through multiple knobs, or poorly with just a single knob. Thus, what is needed is a system and method for providing touchpad input to any system that utilizes knobs, sliding actuators or other non-touchpad means to provide analog input. What is also needed is a system and method for providing electronic devices with input that can be analogized to the turning of knobs or other similar actuators.
It should be noted that one method of scrolling is through the use of a dedicated or non-dedicated scroll zone on a vertical or horizontal edge of a touchpad. The user slides a finger up or down along the scroll zone. However, when a user reaches an edge of a scrolling zone, the user is required to lift a finger and move it back in order to keep scrolling in a same direction. This is a disadvantage of a linear scrolling region, regardless of whether or not the scrolling region is dedicated to scrolling or not.
Before describing the invention in more detail it is useful to describe the capacitance-sensitive touchpad technology of CIRQUE® Corporation. The CIRQUE™ Corporation touchpad is a mutual capacitance-sensing device and an example is illustrated in FIG. 1. In this touchpad, a grid of row and column electrodes is used to define the touch-sensitive area of the touchpad. Typically, the touchpad is a rectangular grid of approximately 16 by 12 electrodes, or 8 by 6 electrodes when there are space constraints. Interlaced with these row and column electrodes is a single sense electrode. All position measurements are made through the sense electrode.
In more detail, FIG. 1 shows a capacitance sensitive touchpad 10 as taught by Cirque® Corporation includes a grid of row (12) and column (14) (or X and Y) electrodes in a touchpad electrode grid. All measurements of touchpad parameters are taken from a single sense electrode 16 also disposed on the touchpad electrode grid, and not from the X or Y electrodes 12, 14. No fixed reference point is used for measurements. Touchpad sensor control circuitry 20 generates signals from P,N generators 22, 24 that are sent directly to the X and Y electrodes 12, 14 in various patterns. Accordingly, there is a one-to-one correspondence between the number of electrodes on the touchpad electrode grid, and the number of drive pins on the touchpad sensor control circuitry 20.
The touchpad 10 does not depend upon an absolute capacitive measurement to determine the location of a finger (or other capacitive object) on the touchpad surface. The touchpad 10 measures an imbalance in electrical charge to the sense line 16. When no pointing object is on the touchpad 10, the touchpad sensor control circuitry 20 is in a balanced state, and there is no signal on the sense line 16. There may or may not be a capacitive charge on the electrodes 12, 14. In the methodology of CIRQUE® Corporation, that is irrelevant. When a pointing device creates imbalance because of capacitive coupling, a change in capacitance occurs on the plurality of electrodes 12, 14 that comprise the touchpad electrode grid. What is measured is the change in capacitance, and not the absolute capacitance value on the electrodes 12, 14. The touchpad 10 determines the change in capacitance by measuring the amount of charge that must be injected onto the sense line 16 to reestablish or regain balance on the sense line.
The touchpad 10 must make two complete measurement cycles for the X electrodes 12 and for the Y electrodes 14 (four complete measurements) in order to determine the position of a pointing object such as a finger. The steps are as follows for both the X 12 and the Y 14 electrodes:
First, a group of electrodes (say a select group of the X electrodes 12) are driven with a first signal from P, N generator 22 and a first measurement using mutual capacitance measurement device 26 is taken to determine the location of the largest signal. However, it is not possible from this one measurement to know whether the finger is on one side or the other of the closest electrode to the largest signal.
Next, shifting by one electrode to one side of the closest electrode, the group of electrodes is again driven with a signal. In other words, the electrode immediately to the one side of the group is added, while the electrode on the opposite side of the original group is no longer driven.
Third, the new group of electrodes is driven and a second measurement is taken.
Finally, using an equation that compares the magnitude of the two signals measured, the location of the finger is determined.
Accordingly, the touchpad 10 measures a change in capacitance in order to determine the location of a finger. All of this hardware and the methodology described above assume that the touchpad sensor control circuitry 20 is directly driving the electrodes 12, 14 of the touchpad 10. Thus, for a typical 12×16 electrode grid touchpad, there are a total of 28 pins (12+16=28) available from the touchpad sensor control circuitry 20 that are used to drive the electrodes 12, 14 of the electrode grid.
The sensitivity or resolution of the CIRQUE® Corporation touchpad is much higher than the 16 by 12 grid of row and column electrodes implies. The resolution is typically on the order of 960 counts per inch, or greater. The exact resolution is determined by the sensitivity of the components, the spacing between the electrodes on the same rows and columns, and other factors that are not material to the present invention.
Although the CIRQUE® touchpad described above uses a grid of X and Y electrodes and a separate and single sense electrode, the sense electrode can also be the X or Y electrodes by using multiplexing. Either design will enable the present invention to function.
The underlying technology for the CIRQUE® Corporation touchpad is based on capacitive sensors. However, other touchpad technologies can also be used for the present invention. These other proximity-sensitive and touch-sensitive touchpad technologies include electromagnetic, inductive, pressure sensing, electrostatic, ultrasonic, optical, resistive membrane, semi-conductive membrane or other finger or stylus-responsive technology.